As I'm sure you've already read, Hurricane Gustav appears to be heading for New Orleans, right on the heels of the Katrina anniversary.
There is much you can do and better people than me pointing out where to spend your money (and please do, even if it's only five bucks).
BlackAmazon: INCITE! RIGHT NOW (I did)
brownfemipower: Critical Resistance
Slyvia: has a ton of links on how you can help
los anjalis: Gustav Information Network
Nezua: is on it as always
Kristin: gives us more than a few resources
And many others are keeping up to date on what's happening.
Kate Harding: selections from The CNN article on Gustav
David: why you don't pray ill to befall people
Professor Black Woman: gives us details
Bint: asks us to keep her family in our prayers
I will keep you up to date as I read more.
*edit* Infoshop will be blogging along with whatever happens as they can